Spectacle lens edge simulation tool and method for defining a lens shape with said tool

Abstract

The present invention relates to a lens edge simulation tool ( 10 ) for measuring the fitment of a lens edge profile (LEP) with respect to a frame groove profile (FGP) of a spectacle frame ( 20 ), the lens edge simulation tool ( 10 ) having a defined edge profile (STP) like a lens edge profile (LEP) of a lens ( 6 ) being machined by a defined edger machine ( 4 ), the defined edge profile (STP) comprising a bevel portion ( 11 ) protruding towards a protrusion direction (A), wherein the lens edge simulation tool ( 10 ) further comprises a probe ( 15 ) provided at a distal end tip portion ( 14 ) of the bevel portion ( 11 ) and being moveable (M) along the protrusion direction (A) between a retracted position in which the probe ( 15 ) does not protrude from the defined edge profile (STP) and an extension position in which the probe ( 15 ) protrudes from the distal end tip portion ( 14 ). The present invention further relates to a system ( 1 ) and method for defining a lens shape for a machined lens ( 6 ) adapted to fit into a frame groove ( 21 ) of a spectacle frame ( 20 ).

The invention claimed is: 
     
       1. A lens edge simulation tool for measuring the fitment of a lens edge profile with respect to a frame groove profile of a spectacle frame, the lens edge simulation tool having a defined edge profile like a lens edge profile of a lens being machined by a defined edger machine, the defined edge profile comprising a bevel portion protruding towards a protrusion direction (A),
 wherein the lens edge simulation tool further comprises a probe integrated in the bevel portion and provided at a distal end tip portion of the bevel portion and being axially moveable with respect to the bevel portion along the protrusion direction between a retracted position in which the probe does not protrude from the defined edge profile and an extension position in which the probe protrudes from the distal end tip portion. 
 
     
     
       2. The lens edge simulation tool according to  claim 1 , wherein the defined edge profile further comprises two lateral portions each facing towards the protrusion direction and extending at opposite sides of the bevel portion and away from one another. 
     
     
       3. The lens edge simulation tool according to  claim 1 , wherein the probe has the same dimensions like a tracer pin of a tracer for determining a frame groove periphery or wherein the probe has a spherical or partially spherical or hemispherical or rounded shape. 
     
     
       4. The lens edge simulation tool according to  claim 1 , wherein the probe is biased towards the extension position, and/or wherein the probe is releasably provided to the defined edge profile. 
     
     
       5. The lens edge simulation tool according to  claim 1 , wherein the bevel portion tapers towards the protrusion direction (A). 
     
     
       6. A system for defining a lens shape for a machined lens adapted to fit into a frame groove of a spectacle frame, comprising:
 a holder for holding a spectacle frame, 
 a lens edge simulation tool according to  claim 1  and provided such that it can be introduced with its bevel portion and probe into a frame groove of the spectacle frame held by the holder at least at one position along a frame groove periphery. 
 
     
     
       7. The system according to  claim 6 , wherein the lens edge simulation tool is supported in a tiltable manner at least about an axis extending orthogonally to the protrusion direction in side view of the lens edge simulation tool. 
     
     
       8. The system according to  claim 6 , further comprising a tracer for determining the frame groove periphery at a bottom of the frame groove of the spectacle frame being held by the holder by relative movement of the tracer with respect to the holder or spectacle frame,
 wherein the tracer comprises a camera, or wherein the tracer comprises a tracer pin configured to rest at the bottom of the frame groove during determination of the frame groove periphery during the relative movement. 
 
     
     
       9. The system according to  claim 6 , further comprising an edger machine having an edging profile for machining the defined lens edge profile, wherein the edging profile comprises a groove representing the negative layout or contour of the lens edge profile to be machined. 
     
     
       10. The system according to  claim 6 , further comprising a control unit for controlling the holder and/or the lens edge simulation tool and/or the edger machine for controlling a relative movement of the holder with respect to the lens edge simulation tool and/or a tracer for determining a frame groove periphery. 
     
     
       11. The system according to  claim 10 , wherein the control unit is configured to provide and/or determine
 data, like a lens shape compensation value, representing an offset of the lens edge simulation tool introduced in the frame groove with respect to a bottom of the frame groove based on the extension position of the probe with respect to the retracted position or distal end tip portion based on data received from the lens edge simulation tool, and 
 also data representing the frame groove periphery, and/or 
 also data representing a lens edge periphery of a machined lens based on the frame groove periphery in conjunction with the determined offset or shape compensation value and also based on data representing the relative tiltable angle α of the lens edge simulation tool, 
 wherein the control unit is configured to provide said data to the edger machine to control the edger machine to machine a lens based on said data. 
 
     
     
       12. A method for defining a lens shape for the machined lens adapted to fit into a frame groove of a spectacle frame, comprising the steps of:
 a) Determining a frame groove periphery at a bottom of the frame groove of the spectacle frame, 
 b) Providing the lens edge simulation tool, according to  claim 1 , having the defined edge profile comprising the bevel portion protruding towards the protrusion direction, wherein the lens edge simulation tool comprises the probe provided at the distal end tip portion of the bevel portion and being moveable along the protrusion direction between the retracted position in which the probe does not protrude from the defined edge profile and an extension position in which the probe protrudes from the distal end tip portion, 
 c) Introducing the lens edge simulation tool with its bevel portion and probe into the frame groove at least at one position along the frame groove periphery so that the lens edge simulation tool rests on the spectacle frame in the protrusion direction and the probe rests on the bottom of the frame groove, 
 d) Determining an offset of the so introduced lens edge simulation tool with respect to the frame groove based on the extension position of the probe with respect to the retracted position or distal end tip portion, and 
 e) Determining a lens edge periphery for the machined lens based on the frame groove periphery in conjunction with the determined offset, based on the frame groove periphery compensated by a shape compensation value based on or derived from the amount of offset. 
 
     
     
       13. The method according to  claim 12 , wherein the lens edge simulation tool and the frame groove are relatively and freely tilted with respect to each other, to align them and preferably their planes of osculation, in a tilt position in which the determined offset is minimum and/or in which lateral portions restrict the tilt angle α relative to the spectacle frame due to contact between them. 
     
     
       14. The method according to  claim 12 , further comprising the following step:
 f) Machining the lens with the edger machine based on the determined lens edge periphery so that the machined lens fits into the frame groove of the spectacle frame. 
 
     
     
       15. The method according to  claim 14 , 
       wherein at least steps b) to e) are performed on a computer, wherein the computer provides the lens edge periphery to an edger machine for performing step f). 
     
     
       16. The lens edge simulation tool according to  claim 3 , wherein the probe has a diameter D of 0.1 to 4 mm. 
     
     
       17. The system according to  claim 8 , wherein the probe and the tracer pin have the same shape or size. 
     
     
       18. The system according to  claim 10 , wherein the control unit further controls a relative movement of a lens to be machined with respect to the edger machine. 
     
     
       19. The method according to  claim 13 , wherein the lens edge simulation tool and the frame groove are relatively and freely tilted with respect to each other, to align them and their planes of osculation in a tilt position in which the lateral portions restrict the tilt angle α relative to the spectacle frame due to substantially symmetrical contact between them in side view of the lens edge simulation tool. 
     
     
       20. The method according to  claim 14 , wherein all steps are performed on a system for defining a lens shape for a machined lens adapted to fit into a frame groove of a spectacle frame, comprising:
 a holder for holding a spectacle frame, 
 a lens edge simulation tool provided such that it can be introduced with its bevel portion and probe into a frame groove of the spectacle frame held by the holder at least at one position along a frame groove periphery, 
 wherein the lens edge simulation tool measures the fitment of a lens edge profile with respect to a frame groove profile of a spectacle frame, the lens edge simulation tool having a defined edge profile like a lens edge profile of a lens being machined by a defined edger machine, the defined edge profile comprising a bevel portion protruding towards a protrusion direction (A), and 
 wherein the lens edge simulation tool further comprises a probe integrated in the bevel portion and provided at a distal end tip portion of the bevel portion and being axially moveable with respect to the bevel portion along the protrusion direction between a retracted position in which the probe does not protrude from the defined edge profile and an extension position in which the probe protrudes from the distal end tip portion.